Fish feed can serve as a pathway for radionuclides to enter aquatic food chains, posing potential health risks to both fish and humans. This study investigated the levels of naturally occurring radionuclides—potassium-40 (40K), radium-226 (226Ra), and thorium-232 (232Th)—in fifteen commercial fish feed samples collected from regional markets. Samples were prepared by drying, grinding, and sieving, followed by sealing for 28–30 days to achieve secular equilibrium. Radionuclide activity was measured using high-purity germanium (HPGe) gamma spectrometry with appropriate energy and efficiency calibration. Results revealed that 40K exhibited the highest activity (range: 98.11–610.87 Bq/kg; mean: 312.3 Bq/kg), followed by 226Ra (4.32–15.00 Bq/kg; mean: 9.57 Bq/kg) and 232Th (3.21–11.20 Bq/kg; mean: 7.59 Bq/kg). Statistical analyses indicated moderate variability in 40K and more uniform distribution for 226Ra and 232Th, with a moderate positive correlation between 40K and 232Th (r = 0.62). The committed effective dose (CED) for adult consumers, calculated based on radionuclide activity and standard dose conversion factors, remained below the recommended public limit of 1 mSv/year. The findings suggest that, although radionuclide concentrations vary across feed brands, the overall radiological risk from consuming fish fed with these products is within safe limits. This study provides essential baseline data for monitoring radionuclide contamination in aquaculture feeds and highlights the importance of continuous assessment to ensure food safety and public health.
A systematic comparison of gamma-radiation methods was performed: passive method (measurement of natural radioactivity), neutron activation analysis (NAA) and prompt gamma neutron activation analysis (PGNAA) were used for the elemental analysis of a sample of lanthanum oxide (La2O3). The PGNAA method was found to provide the optimal combination of convergence to true value and speed. However, NAA achieved the lowest minimum detectable mass due to its low background signal compared to PGNAA.
Grains contain varying levels of radionuclides, and humans are exposed to these radionuclides both externally and internally through daily consumption. In this study, concentrations of alpha-emitting radionuclides were measured in commonly consumed imported grains in northeastern Iraq using CR-39 solid-state nuclear track detectors (SSNTDs). The primary objective was to evaluate the safety of these grains for human consumption. The measured activity concentrations of 222Rn, 226Ra, 238U, and radon daughters deposited on chamber walls (POW) and detector face surfaces (POS) ranged from 96.0 to 187.5 Bq/m3, 0.30 to 0.58 Bq/kg, 0.051 to 0.185 ppm, 29.7 to 58.0 Bq/m3, and 16.1 to 31.5 Bq/m3, with means of 133.6 Bq/m3, 0.41 Bq/kg, 0.102 ppm, 41.3 Bq/m3, and 22.4 Bq/m3, all well below internationally accepted safety limits. Furthermore, the annual ingestion dose (), excess lifetime cancer risk (), and effective external organ dose () were estimated for three age groups based on the consumption of the studied grains. The calculated radiological indices generally remained below global reference values. Statistical analyses (skewness, kurtosis, Shapiro-Wilk test, and P-values) explored relationships alpha emitters concentrations and radiological risk parameters across all age groups.
The accurate characterization of mixed neutron–photon radiation fields generated during neutron irradiation of environmental samples is essential for dosimetric optimization and radiological protection in activation analysis facilities. In the present work, a Monte Carlo simulation study was performed using the Particle and Heavy Ion Transport code System (PHITS) version 3.35 to quantify the spatial distribution and attenuation behavior of neutron and photon absorbed doses in a polyethylene shuttle designed for soil sample irradiation.The three-dimensional geometry of the irradiation capsule, moderator structure, and surrounding air environment was modeled in detail, and absorbed doses were evaluated at radial distances ranging from direct contact up to 1 m under zero-cooling-time conditions, corresponding to prompt radiation fields during irradiation.This study provides a strong neutron dose dominance in the near-field region, with absorbed doses approaching 60 Gy, followed by a rapid attenuation beyond 5 cm driven by geometric dispersion and neutron leakage. The photon component, although lower in magnitude, exhibits measurable buildup effects at intermediate distances due to prompt gamma production from neutron interactions. All Monte Carlo statistical uncertainties were maintained below 2%.This work provides a high-resolution dosimetric database describing the coupled neutron–photon radiation field around a realistic polyethylene irradiation shuttle, offering quantitative information that is currently scarce in the literature and supporting dosimetric optimization and radiation protection in neutron activation analysis facilities.
This work is a study of the random evolution of fission chains. To investigate the fission pulse initiation time of a pulse reactor under δ-source initiation, we started from Hansen's formula and derived a probability formula for simultaneous initiation by multiple chains by leveraging the characteristics of the Gamma distribution in probability theory. This formula describes the probability density of neutron number and time under δ-source initiation. It can be used to predict the initiation time distribution of a pulse reactor driven by a δ-source. To validate the formula, we conducted verification experiments on the CFBR-Ⅱ pulse reactor. The resulting initiation time distribution is consistent with the predictions of our model.
This study examined the natural radioactivity due to 226Ra, 232Th and 40K and radiation dose of new university campus, Dennis Osadebay University (DOU), in Asaba, southern part of Nigeria. Measured activity concentrations of radionuclides in soil showed a normal distribution and were ranged from 20.98 to 159.81 (73.32±31.11) Bq/kg for 226Ra, 26.7 to 95.07 (58.38±16.04) Bq/kg for 232Th and 108.33 to 316.44 (224.89±51.79) Bq/kg for 40K. While the average concentrations of 40K were about 1.5 times lower than the world average with 63% contribution to the total radioactivity content of the soil, the concentrations of 226Ra and 232Th were 2.2 and 1.3 times higher than the global average with about 21% and 16% contribution. The average radiation absorbed dose (78.51 nGy/h) and annual effective dose (0.10 mSv/y) exceeded global average of 59.0 nGy/h and 0.07 mSv/y respectively. Based on this and other radiological indices, the soil natural radiation is above that of normal background radiation level with potential radiological threat to the university community and general public.
The effect of an external magnetic field with an intensity Bext ≈ (0−30) kT on the collimation of proton beams and energy deposition towards pre-compressed fuel with a density ρc ≈ (300−1000) g.cm-3 was investigated in laser-solid interactions using the Geant4 simulation toolkit. Three types of energy distributions were considered for the proton beams: Gaussian, Maxwellian, and Exponential. Geant4 simulations indicated that with an external magnetic field amplitude Bext ≈ (0−20) kT, the energy deposition of proton beams gradually increased towards the over-dense plasma for for all value of fuel density and all types of proton beams distribution functions, peaking at Bext ≈ 10 kT for the commenly used fuel density interval ρc = (292 −658) g.cm-3. Moreover, the results confirm that for the magnetic field intensities greater than the value 20 kT, the energy deposition of protons saturated, showing steady-state behavior and was not affected by increasing the magnetic field intensity. It can be concluded that the optimum deposited energy was obtained for the protons with Gaussian energy distribution function, a magnetic field value of about Bext ≈ 5 kT and a main fuel density of about ρc ≈ 300 g.cm-3.
The background radiation of construction materials in both raw and final forms was investigated. Samples of raw materials (gravel, sand, and clay, limestone, and gypsum) were grouped, whereas final products (cement, Terrazzo tiles (Kashi), bricks, and plaster) were the final product samples. Background radiation exposure due to these materials was assessed using a portable dosimeter. Radiological Evaluations of Absorbed Dose (D), Annual Effective Dose (AED), and Excess Lifetime Cancer Risk (ELCR) in all samples were calculated. It was found that the final product samples had higher radiation than their respective raw materials. This increase may be attributed, at least in part, to industrial processing and to the possible concentration of naturally occurring radionuclides during manufacturing. Despite this variability, all measured values for both raw and final materials fell within internationally recommended limits of natural background radiation exposure. Thus, the construction materials studied in Najaf Governorate are not radiological hazards for use in building applications, and there is no significant risk to the health of workers or residents due to long exposure.
This work presents a comparative neutronic assessment of conventional UO2 and three thorium-based fuels, namely (Th-235U)O2, (Th-233U)O2, and (Th-233U-235U)O2, in a Westinghouse-SMR-like core under several beginning-of-cycle (BOC) loading arrangements. The study distinguishes the respective roles of fissile vector and loading pattern in governing burnup behavior, fissile sustainability, isotopic evolution, fission-product poisoning, neutron-flux redistribution, assembly-wise radial power peaking (PPF), reactivity feedback, and kinetic response. The U-233-supported thorium option provides the strongest neutronic performance, with Core-3b reaching the highest discharge burnup of 33.37 GWd/tHM, compared with 26.86 GWd/tHM for the reference UO2 core. The same fuel family also yields the flattest radial power distributions, whereas the strongest assembly-wise power peaking is observed in the less favorable (Th-235U)O2 loading patterns. The hybrid (Th-233U-235U)O2 option consistently shows improved behavior and emerges as the most balanced compromise among cycle extension, fissile retention, radial power shaping, and safety-related neutronic characteristics. Thorium-containing configurations preserve a higher fissile inventory ratio and strongly suppress plutonium buildup, but U-233-rich cases exhibit weaker moderator feedback and less favorable kinetic characteristics.
Globally, inorganic fertilizers have become essential for enhancing soil quality and boosting agricultural yield. These fertilizers, such as NPK (nitrogen, phosphate, and potassium), have the potential to alter the concentration of radionuclides in the soil. This paper presents the findings of gamma spectrometric analyses of natural radionuclides, specifically 226Ra, 232Th, and 40K, in soil samples obtained from various sites in the Al-Wihda district of Baghdad, Iraq, where local farmers utilize different inorganic fertilizers to improve crop yields. The results were also compared with samples from the fallow regions, which had not seen agricultural activities for a long time. On average, the respective concentrations of 226Ra, 232Th, and 40K in fertilized soil were 11.84±1.63, 10.58±1.51, and 421.99±20.67 Bqkg-1, while the concentrations of these radionuclides in unfertilized soil were 6.24±0.92, 7.48±1.07, and 356.98±17.49 Bqkg-1. The findings demonstrate that the application of inorganic fertilizers to enhance crop productivity may elevate activity concentrations, which would increase the exposure of farmers in such fields. However, the results for radium equivalent activity, absorbed dose rate, annual effective dose, and external hazard index were within the global limits and did not cause any radiological risk to the farmers.
This study evaluates neutron backscattering for diagnosing a laboratory-scale pilot column and compares its performance with gamma scanning on the same device. A 127-cm-diameter column was investigated using a Co-60 source with a NaI(Tl) detector for gamma scanning and an Am-Be source with a He-3 detector for neutron backscattering. Results show that neutron backscattering cannot identify empty trays but detects water hold-up with an average efficiency of 86.21 %. Gamma scanning locates empty trays but measures only 24.59 % of water. Neutron backscattering provides complementary information and more accurate liquid estimation, offering additional details beyond those obtained by gamma scanning.
In this study, the feasibility of producing two radioisotopes, 152Eu and 154Eu, through irradiation of natural europium was investigated using the MCNPX 2.6 code and MATLAB computational software. 152Eu and 154Eu radioisotopes are used as standard radioactive sources in industrial and research applications for the calibration of gamma radiation measuring systems. The sample was simulated in the B1 irradiation location of the Tehran Research Reactor core, at a point with the highest neutron flux (1.31×1013 n/cm2s). To optimize reactor operation cycles and manage radioactive waste, the optimal cooling time was set to 12 days. The activity of the produced isotopes was examined and evaluated for a 7-day irradiation period and a 12-day cooling period. Results indicated that, in addition to 152Eu, recognized as a calibration source in the industry, 154Eu could also be introduced and utilized as an efficient and suitable option for gamma spectrometry system calibration. Furthermore, a reasonable difference was observed between the results of the two methods, indicating that MATLAB, for several decades its simplicity and speed in providing initial approximations, serves as a suitable option for preliminary assessments. However, for more precise evaluations and consideration of all details, the MCNPX code is a more appropriate solution. Therefore, it can be concluded that while MATLAB can provide quick initial estimates, the MCNPX code provides more accurate evaluations by calculating additional complexities. This insight allows researchers to choose the most appropriate computational tools based on the specific needs of their work.
Newborns exposed to uranium face significant health risks stemming from its radioactive and chemical properties. Exposure during this critical period can compromise organ development, restrict growth, and cause genetic harm. The harmful effects are enhanced when exposure occurs from contaminated air, water, or materials used around newborns. Therefore, this study analyzed areas of possible exposure to uranium-238 (238U) by assessing a range of materials that are routinely used by or with newborns in Al-Najaf Governorate, Iraq. The samples of material were divided into two groups: solid (44 samples) and liquid (76 samples). The solid materials included baby powder, soap, lotion for clothing, lotion for breastfeeding, cream, and canned milk. The liquid group included shampoo, bottled water, filtered water, breast milk, syrup drugs, and injection drugs. Uranium-238 concentrations were measured using a CR-39 nuclear track detector based on a calibration curve prepared from a standard uranium source. The radiological hazard parameters, such as annual effective dose (EU) and risk of an excess cancer fatality per million persons (RECFPMP), were calculated in two group samples using theoretical equations. The average values of 238U concentrations in the solid and liquid samples ranged from 0.659±0.023 ppm and 0.689±0.005 ppb, respectively, while the activity concentrations were 8.133±0.280 Bq/kg and 0.017±0.0001 Bq/L, respectively. Moreover, the average values for EU were found to be 19.012 μSv/y in the solid samples and 142.943 nSv/y in the liquid samples. Furthermore, the average RECFPMP values were found to be 73.196×10-6 in the solid samples, and 550.331×10-9 in the liquid samples. However, all results were within the internationally accepted limits, including those of the ICRP, UNSCEAR, and WHO. Therefore, it can be concluded that these two types of medications available in Iraqi pharmacies pose no risk to human health. However, all results were within the internationally accepted limits. Therefore, it can be concluded that these two types of internal and external materials available in Iraqi pharmacies pose no risk to the health of newborns.
DSRS presents a growing radiological and security challenge, particularly in low and middle-income countries. These sources, widely used in industry, medicine, and research, often retain their activity even after their intended use has ended. Without appropriate regulatory control and end-of-life management, DSRS can become orphan sources, posing environmental, health, and proliferation risks. This review consolidates international practices and IAEA guidance regarding DSRS classification, regulatory frameworks, dismantling protocols, and long-term disposal strategies. Special attention is given to the management of sealed radioactive sources across Categories 1 to 5. While Categories 1 and 2 pose the highest radiological risks due to their high activity levels and are subject to strict international repatriation and dismantling protocols, Categories 3 to 5, though individually less hazardous, are far more numerous and widely distributed, making them particularly vulnerable to loss, abandonment, or misuse. This paper reviews current practices and highlights innovative shielding container designs, particularly those utilizing layered materials such as concrete, lead, and High-Density Polyethylene (HDPE), which have been optimized through Monte Carlo simulations to ensure safety during the transport and interim storage of DSRS. Real-world case studies further underscore the importance of coordinated regulatory, technical, and operational measures to mitigate radiological risks across the full spectrum of DSRS categories.
Twenty tap water samples were collected from various sites across Iraqi Kurdistan and subjected to comprehensive analysis aimed at monitoring radon activity concentrations alongside key physicochemical parameters. Radon measurements were carried out using a RAD7 radon detector, and the obtained results were evaluated against internationally recommended guidelines and benchmarked with findings from comparable regional studies. Radon activity concentrations in the collected samples ranged between 0.45 and 3.85 Bq/L, yielding a mean of 1.40 Bq/L, values that fall well within the permissible limits established by both the World Health Organization (WHO) and the United States Environmental Protection Agency (USEPA). Based on these measurements, both the annual ingestion effective dose and the annual inhalation effective dose were calculated across three distinct age categories: infants, children, and adults. The resulting radiological health risk estimates remained, in general, below the WHO threshold of 100 μSv/y. Among the three age groups, infants consistently recorded the highest annual ingestion and annual inhalation effective dose values, while the ingestion pathway was found to contribute a greater dose burden than inhalation across all groups. Statistical evaluation indicated a significant correlation between radon concentration and the associated radiological health risk parameters; however, no meaningful relationship was established between radon levels and the majority of the physicochemical characteristics examined in this study.
Global nuclear energy is witnessing a measurable resurgence as a strategic solution for climate mitigation and energy security. As of 2024, 417 nuclear reactors operating in 32 countries generate approximately 2,667 TWh about 8.96% of global electricity. Expansion is geographically asymmetric: China leads with 24 reactors under construction and 43 proposed, while legacy nuclear nations like the United States and France face limited additions but significant retirements. According to IEA and IAEA projections, global capacity must grow from 416 GW in 2024 to 874–1,017 GW by 2050 to support net-zero pathways. However, the IAEA reports 215 reactors have been permanently retired globally, including 41 in the U.S. and 36 in the U.K., threatening net growth unless aggressive deployment continues. Small Modular Reactors (SMRs) and policy reforms offer critical mitigation, with over 127 SMR designs under development globally. This study presents a comprehensive, data-driven analysis of nuclear power’s evolving role, drawing on historical trends, real-time reactor statistics, and authoritative forecasts. The findings underscore nuclear’s indispensable role in a low-carbon energy future, provided current retirement trends are counterbalanced by accelerated licensing, financing, and innovation.
Spallation reactions are the basis of high-flux neutron source development for accelerator-driven systems (ADS), transmutation of radioactive waste, and radioisotope production. Using detailed simulations based on the Monte Carlo framework of the GEANT4 toolkit and the FTFP_BERT_HP physics model, this work offers a systematic approach to optimize spallation target shape and material. Neutron and photon yields from two different target materials, liquid mercury and natural uranium, irradiated with a 1.4 GeV proton beam are investigated. The geometries of the two cylindrical targets were varied in height from 1 cm to 75 cm while keeping the constant diameter at 34.4 cm. The simulations show that uranium emits about 2.5 times as many neutrons as mercury per incident proton, and these are emitted closest to the proton beam entry points. The locations that produce the maximum number of neutrons are found to be 4 cm from the entry points for uranium (52.65 neutrons per proton) and 2 cm from these points in the mercury target (22.9 neutrons per proton). The work shows that uranium is preferred based on neutron yield maximization while minimizing costs, and that there are unique advantages offered by the mercury target regarding thermal properties in continuous operation modes. The data are verified by comparisons with other models presently used in spallation physics.
This study evaluates the distribution, radiological significance, and controlling factors of naturally occurring radionuclides in agricultural soils from the Tosham Ring Complex (TRC), north-western India, a region underlain by high heat-producing granites of the Malani Igneous Suite. Nineteen soil samples were analyzed using high-purity germanium (HPGe) gamma spectrometry to determine the activity concentrations of 40K, 226Ra, and 232Th. The measured activity concentrations of 40K ranged from 395.2 to 558.6 Bq kg-1 (mean: 464.0 ± 40.7 Bq kg-1), while 226Ra and 232Th ranged from 32.8–66.4 Bq kg-1 (mean: 45.3 ± 9.3 Bq kg-1) and 19.4–38.9 Bq kg-1 (mean: 28.4 ± 5.5 Bq kg-1), respectively. The mean activities of 40K and 226Ra exceed global average values, whereas 232Th remains within the worldwide range. Radiological hazard indices, including radium equivalent activity (Raeq), absorbed dose rate (AAD), annual effective dose equivalent (AEDE), annual gonadal equivalent dose (AGED), gamma index (Iγ), and internal and external hazard indices, were calculated to assess potential health risks. Coreelation analysis indicates strong positive correlations between 226Ra and 232Th (r ≈ 0.91) and radiological hazard indices (r > 0.95, p< 0.0001), suggesting their contributor to estimate radiological risk. In contrast, 40K shows comparatively weaker correlations (r = 0.62, p < 0.005). Principal component analysis further confirms that with PC1 ( 226Ra and 232Th) 94.94% of total variance and representing a general radioactivity intensity factor. The calculated radiological parameters remain within internationally recommended safety limits, indicating low radiological risk for the studied soils and providing baseline data for natural radioactivity in the region.
This study evaluates natural radioactivity levels in building materials used in Penang, Malaysia. Soil, cement, and brick samples were analyzed for radionuclides U-238, Th-232, and K-40 using High Purity Germanium (HPGe) gamma spectrometry. Samples were stored airtight to ensure radioactive equilibrium before measurement. Results showed that concentrations of U-238, Th-232, and K-40 were below global reference values recommended by NCRP and UNSCEAR. Cement bricks recorded the highest radionuclide concentrations and radiation hazard indices, including Radium Equivalent Activity, internal hazard index, and external hazard index, while waterproofing cement had the lowest. Raeq values for all samples were below the safety limit of 370 Bq/kg, and annual dose rates were under 70 μSv/year, meeting European Commission guidelines. Granite and sand soils exhibited lower radionuclide concentrations compared to global averages, except for K-40 in granite soil, which exceeded values reported in other studies. While all materials remain within safety thresholds, elevated radiation levels in cement bricks warrant further consideration. This study offers valuable insights into radiological hazard analysis, supporting sustainable building practices in Malaysia.
In this study, the neutron activation analysis method was applied to determine 23 major and trace elements (Na, Al, K, Sc, Ti, V, Cr, Mn, Fe, Co, Zn, As, Rb, Cs, La, Ce, Sm, Eu, Dy, Yb, Hf, Th, and U) in the surface sediments of the Karnaphuli River beside a major industrial and port city in Bangladesh to assess their pollution levels and ecological risks. Spatial concentration analysis showed relatively large variability for Cr, Fe, As, Rb, La, Ce, Sm, Yb, Hf, Th, and U (RSD: 33.1–75.3%) compared with the other analyzed elements, indicating strong anthropogenic influences in the river basin. Though the Modified Degree of Contamination represents a very low degree of contamination at most of the sampling points, the Enrichment Factor, Geo-accumulation Index, and Pollution Load Index showed remarkable pollution status, which would be vulnerable to long-term accumulation of these elements in the river. Concern arises due to the high EF value of Rb (0.56 to 5.12) with a mean value of EF = 2.58, indicating Karnaphuli River is minorly enriched by Rb. The potential ecological risk index and element-specific potential ecological risk factors show the River is at a low-risk level. Additional sediment toxicity indices including toxic units and the biological risk index further indicate a low probability of biological toxicity in the Karnaphuli River sediments. Assessment of human health hazards through hazard index and carcinogenic risk shows no concern, but the elevated values for children may face potential health risks in the future. However, sediment quality guidelines for Cr and As indicate a potential concern at some sampling points of the river. This study recommends that appropriate measures must be implemented to control elemental pollution in the river.
